Method and device for the production of a covered elastic yarn and for automatic replacement of feeds spools

ABSTRACT

The device has: a first interlacing jet ( 19 ); a feed path of the covering yarn (FT) and a feed path of the elastic yarn (F 1 ; F 2 ) towards the first interlacing jet; supporting elements ( 37 A,  37 B) for spools of elastic yarn (R 1 , R 2 ); winding members ( 54 ) to wind the composite yarn (FC) on the cop being formed (BC); an interruption device to interrupt feed of composite yarn to the cop being formed and start winding the composite yarn on a new winding tube. The supporting elements for the spools of elastic yarn are suitable to support at least a first spool of elastic yarn and at least a second spool of elastic yarn; associated with the first interlacing jet are a retaining member ( 20 ) to withhold an initial free end of the elastic yarn of the second spool and a deflecting element to withhold an initial portion of the second elastic yarn during delivery of the first elastic yarn to the interlacing jet; a sensor to detect interruption of feed of the first elastic yarn to the first interlacing jet; a control to control release of the initial portion after interruption of feed of the first elastic yarn has been detected.

TECHNICAL FIELD

The present invention relates to a method and a device for theproduction of a composite yarn of the type comprising a core part,consisting of at least one elastic yarn, and an external coating,consisting of at least a covering or coating yarn, for example, anessentially non-elastic yarn or in any case a yarn with less elasticitythan the core yarn.

More specifically, the invention relates to a method and a device thatallows the spools of elastic yarn to be replaced in an automatic, simpleand reliable way when they are finished or nearly finished.

STATE OF THE ART

Composite elastic yarns, consisting of an inner elastic yarn, such as asingle filament yarn, made of Lycra®, Elastan, other polyurethane fibersor the like, are frequently used in the production of fabrics andparticularly knitwear, such as hosiery. The elastic yarn is covered by aless elastic yarn, which may be considered essentially non-elastic, suchas a Nylon®, or other polyamide, polyester or equivalent, typically witha multiple filament structure, that is, consisting of a plurality ofstrands. This yarn will henceforth be indicated as covering yarn as itis used to form a sort of coating or covering of the elastic yarn.

The coating of the elastic yarn may be obtained by means of a coveringprocess in which the elastic yarn is coated with a helical winding ofcovering yarn. This process is extremely costly and slow.

A new process of coating or covering elastic yarns has recently becomepopular. This process, known as interlacing or air covering, consists inusing a pneumatic device, commonly called interlacing jet, with aconduit through which the two covering and elastic yarns pass. Apressurized air nozzle delivers a jet of compressed air inside theconduit. The turbulence produced inside the conduit causes interlacingof the covering yarn around the elastic yarn. Devices and methods basedon this technology are described in U.S. Pat. No. 6,393,817, U.S. Pat.No. 5,008,992, U.S. Pat. No. 4,829,757 and U.S. Pat. No. 3,940,917.

This technology uses pneumatic systems originally developed forprocessing multiple filament threads to increase bulk and simultaneouslycombine the single filaments of which they are composed. Examples ofinterlacing jets developed for this application and which can be used tointerlace elastic or elastomer yarns with covering or coating yarns aredescribed in U.S. Pat. No. 5,970,593, U.S. Pat. No. 5,146,660, U.S. Pat.No. 5,010,631, U.S. Pat. No. 4,430,780, EP-B-564400 and JP-A-3279437.

The spools of elastic or elastomer yarn used in systems for theproduction of covered elastic yarn contain much less yarn than that ofthe spools or cops of covering yarn. Typically, the elastic yarn on onespool is sufficient to produce a single cop of composite yarn, while thecovering yarn wound on one cop is sufficient to make several cops ofcomposite yarn. This makes it necessary to change the spools of elasticyarn frequently, between two subsequent covering or coating yarn copchanges. Replacement is manual. In a system generally equipped with aplurality of individual heads, each producing a cop of composite yarn,end-of-yarn sensors are provided to interrupt head operation when therespective spool of elastic yarn is finished. The operator must manuallyreplace the finished spool of elastic yarn, and insert the free end ofthe new elastic yarn into the interlacing jet to start the winding cycleof a new cop of composite yarn. In manual systems, the operator mustalso replace the completed cop with a new tube on which the newcomposite yarn is wound. The delivery of covering yarn is interruptedduring this operation.

This operating method has considerable drawbacks. Firstly, there arenoteworthy downtimes, as a single operator monitors a large number ofworking heads and therefore considerable time may elapse between thespool of elastic yarn finishing and the operation of the operator thatallows the head to start the subsequent winding cycle. Furthermore,specifically to avoid excessive machine downtimes, in some cases thespools of composite yarn may be replaced before they are completelyfinished. The residual yarn cannot be used. This means that aconsiderable amount of elastic yarn is wasted, representing asignificant drawback in view of the high cost per unit of length of thismaterial.

On the other hand, it is not possible for the operator to prepare aspare spool of composite yarn in advance and join the head or initialfree end of the yarn of the spare spool to the tail of the yarn on thespool being processed, which would allow spool change to be preparedwell before it ended and also to use up the entire spool beingprocessed. This operation is not possible due to the fact that thespools of elastic yarn are not unwound holding them stationary, but mustrotate about their axis to deliver the yarn wound thereon. Consequently,it is impossible for the operator to grasp the end or tail of the spoolbeing processed and join it to the initial end of the yarn on the sparespool. This problem does not occur when replacing cops of covering yarnas the cops are unwound without rotating them about their axis. Thisallows head-to-tail joining of the yarns wound on cops intended to beunwound in sequence, ensuring continuous feed of the covering yarn.Furthermore, the cops of covering yarn contain a large amount of yarnand therefore joining operations are carried out at considerableintervals from one another.

Covering yarn texturing devices are provided between the yarn deliverycop and the interlacing jet in some systems (see U.S. Pat. No. 6,393,817and U.S. Pat. No. 5,008,992 in particular). The texturing devicesinclude an oven through which the covering yarn travels. This means thatthe yarn must be fed continuously. In fact, even temporary stopping ofthe yarn in the oven would cause the destruction or unacceptable damagethereof. When the head is stopped, even for only a short time, so thatthe operator can replace the finished spool of elastic yarn, thecovering yarn must be cut upstream of the texturing section, that is,upstream of the oven. When the composite yarn forming head can startagain, as the operator has completed the operations required to replacethe spool and inserted the free end of the elastic yarn into theinterlacing jet, he must re-thread the covering yarn through the entirepath from the cop to the interlacing jet. This entails a lengthydowntime and therefore causes loss of production. The problem can onlybe prevented if the operator is capable of acting promptly to replacethe spool of elastic yarn before the machine automatically cuts thecovering yarn. As a large number of heads, which cannot be synchronized,are monitored by a single operator, it is never possible to act promptlyenough on all heads in the system. Employing a higher number ofoperators, on the other hand, would involve an unacceptable increase inlabor costs.

OBJECTS AND SUMMARY OF THE INVENTION

The object of the present invention is to provide an efficient andreliable method for automatic replacement of the spools of elastic yarnin devices for the production of covered elastic yarn, that is,composite yarn comprising an elastic core and a coating formed by one ormore covering yarns.

According to a different aspect, the object of the present invention isto provide a device for the efficient and reliable continuous productionof cops of composite yarn with automatic replacement of the elastomerspools without requiring to interrupt the covering yarn.

Essentially, according to a first aspect a method is provided comprisingthe phases of:

-   -   feeding the covering yarn in an essentially continuous way along        a feed path, through at least a first interlacing jet    -   delivering a first elastic yarn from a first spool through the        first interlacing jet;    -   covering the first elastic yarn with said covering yarn to form        the composite yarn and winding the composite yarn on a cop;    -   preparing a second spool of a second elastic yarn in a stand-by        position;    -   withholding an initial portion of said second elastic yarn in        proximity to said first interlacing jet;    -   when delivery of the first elastic yarn is interrupted,        replacing the cop of composite yarn with a new tube;    -   releasing said initial portion of the second elastic yarn;    -   joining said covering yarn and said second elastic yarn using        the first interlacing jet;    -   resuming production of the composite yarn covering the second        elastic yarn with said covering yarn and winding the composite        yarn on said new tube.

In a possible embodiment, the first interlacing jet is movable withrespect to the yarns, such that joining of the covering yarn and thesecond elastic yarn by means of the first interlacing jet is obtained bymoving the interlacing jet towards the second elastic yarn. The initialfree end of the second elastic yarn is withheld by a retaining memberwhile the second elastic yarn is in a stand-by position. When the secondelastic yarn shall replace the first elastic yarn, the first interlacingjet is moved toward the second elastic yarn which enters the jet and isreleased from said retaining member.

In a further advantageous embodiment of the method according to theinvention, the initial free end of the second elastic yarn is withheldby a retaining member, and the initial portion of the second elasticyarn can be engaged by a deflecting element. The latter is controlled torelease the initial portion of the second elastic yarn when feed thereoftowards the interlacing jet is required to start.

The deflecting element can be designed to withhold the second elasticyarn out of the first interlacing jet, while the second elastic yarn isdisposed to be automatically inserted into said first interlacing jetwhen it is released from said deflecting element. Advantageously, thesecond elastic yarn can be inserted into the first interlacing jetthrough the effect of the tension exerted by the retaining member.

In a different embodiment, the second elastic yarn is inserted into thefirst interlacing jet and withheld therein, standing by for interruptionof the first elastic yarn.

In a possible embodiment of the method according to the invention, whendelivery of said first elastic yarn is interrupted, the firstinterlacing jet is temporarily made to stop operating while the coveringyarn continues to be fed therethrough; after the second elastic yarnfrom the second spool starts to be delivered through the firstinterlacing jet, said first interlacing jet is re-activated to join thesecond elastic yarn to said covering yarn and resume production of saidcomposite yarn. In this case a single interlacing jet is used both toproduce the composite yarn and to start feeding the elastic yarn of thesecond spool. The second elastic yarn can already be standing by insidethe first interlacing jet when feed of the first elastic yarn isinterrupted.

In a different embodiment, the elastic yarn is instead covered with thecovering yarn by a second interlacing jet, disposed downstream of thefirst interlacing jet along the path of the covering yarn. In this casethe first interlacing jet has the sole function of constraining thesecond elastic yarn to the covering yarn when the empty spool isreplaced with the new spool of elastic yarn. Therefore, the first jetcan be activated only in the exchange phase and remains inoperativeduring the production of composite yarn by the second jet.

According to a different aspect, the invention relates to a methodcomprising the phases of:

-   (a) continuously feeding from the running machine or with the    machine stopped a covering yarn to an air jet interlacing device;-   (b) simultaneously feeding to said interlacing device a first    elastomer yarn being unwound from a first spool, disposed in a    working position, so as to obtain interlacing of said covering yarn    with said elastomer yarn;-   (c) withholding the free end of a second elastomer yarn, wound on a    second spool, disposed in a stand-by position in a retaining area;-   (d) detecting interruption of feed of said first elastomer yarn, to    control, in appropriate time relationship, transfer of said second    spool of elastomer yarn to said working position and transfer of    said first spool of elastomer yarn to said stand-by position;    characterized in that includes the additional phases of:-   (e) performing a relative movement of said covering yarn with    respect to said second elastomer yarn, in proximity to said    retaining area of said free end of the second elastomer yarn, so as    to come into contact with said second elastomer yarn;-   (f) associating said second elastomer yarn with said covering yarn    using an air jet, simultaneously releasing said free end of the    second elastomer yarn, to resume feed of said yarns to said    interlacing device.

According to a different aspect of the invention, a device is providedfor the production of a composite yarn formed by at least an elasticyarn covered with at least a covering yarn, comprising in combination: afirst interlacing jet; a feed path of said covering yarn and a feed pathof said elastic yarn towards said first interlacing jet; supportingmeans for spools of elastic yarn; winding members to wind the compositeyarn on a cop being formed; an interruption device to interrupt feed ofthe composite yarn to said cop being formed and start winding thecomposite yarn on a new winding tube. Characteristically, saidsupporting means for the spools of elastic yarn are suitable to supportat least a first spool of elastic yarn and at least a second spool ofelastic yarn. Moreover, associated with said first interlacing jet are aretaining member to withhold an initial free end of the elastic yarn ofsaid second spool. Also provided are a sensor to detect interruption offeed of the first elastic yarn to the first interlacing jet and acontrol to control release of the initial portion of the second elasticyarn when interruption of feed of the first elastic yarn is detected.

The retaining member can advantageously be a suction member.

According to a possible embodiment, means are provided to move one withrespect to the other the first interlacing jet and the initial portionof the second elastic yarn when the latter is in a standby position. Thesecond elastic yarn thus enters the first interlacing jet when the firstelastic yarn has been interrupted.

According to a further embodiment, associated with the first interlacingjet is also a deflecting element to withhold an initial portion of thesecond elastic yarn during delivery of the first elastic yarn to thefirst interlacing jet.

According to a possible embodiment, the retaining member and thedeflecting element are disposed, with respect to the first interlacingjet, so as to withhold the second elastic yarn out of the firstinterlacing jet. Moreover, the retaining member is designed and arrangedto tension the second elastic yarn causing insertion thereof into thefirst interlacing jet when the deflecting element releases said secondelastic yarn.

Further advantageous features and embodiments of the device and of themethod according to the invention are indicated in the appended claimsand shall be described in greater detail hereunder with reference tosome exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall now be better understood following the descriptionand accompanying drawing, which shows practical non-limiting andexemplary embodiments of the invention. In particular, in the drawing:

FIG. 1 shows a side view of the device complete with the texturing areaof the covering yarn;

FIG. 2 shows a side view of a portion of the device;

FIGS. 3, 4 and 5 show, in various arrangements, a view according toIII-III in FIG. 1 of the winding area of the cop of composite yarn;

FIG. 6 shows a side view similar to the view in FIG. 2 of a modifiedembodiment;

FIGS. 7A and 7B show an approximate front view of the first interlacingjet in two operating conditions;

FIGS. 8, 9 and 10 diagrammatically show a further embodiment of theinvention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

A first embodiment of the invention is shown in FIGS. 1 to 5.

FIG. 1 shows a side view of a system comprising a plurality of windingheads to produce cops of composite yarn with a series of devicesaccording to the invention. Only one head is shown in the figure, theothers being aligned orthogonally to the plane of the figure.

The number 1 generically indicates the area in which the cops B1 ofcovering yarn, for example polyester, nylon or other equivalent yarns,typically a multiple filament yarn, are located. The yarn unwound from acop B1 is fed through a texturing section of conventional type, knownper se and indicated with 3. The texturing area has a heating oven 5, acooling area 6, an area 8 for the false-twisting operation, andterminates with a first pair of rollers 7A, 7B to pick up or feed thetextured covering yarn FT, which is fed to an area 9 in which the spoolsof elastic yarn, the interlacing jet, the actual winding head and allthe members required to change the spools of elastic yarn are located.With the exclusion of the winding head, this area is shown in greaterdetail in FIG. 2.

In the area 9 the yarn FT passes through an oven 11 (to stabilize theyarn) and along its feed path Pft reaches an interlacing jet wherein itcovers the elastic yarn F1 or F2 fed from one or other of the two spoolsR1, R2 carried by supporting means as described below.

A first interlacing jet 2 is disposed along the path Pft, for thepurpose of joining the elastic yarn of a new spool to the texturedcovering yarn FT when a finished spool R1 is replaced with a new spoolR2 of elastic yarn, according to a procedure to be described below. Inthe arrangement in FIG. 2, the interlacing jet 2 is normally inoperativeand is only operated during the phase to start unwinding a new spool ofelastic yarn. The inlet of the interlacing jet 2 is oriented in adirection slanted with respect to the direction from which the yarn FTis fed, so that it is guided inside the interlacing jet 2 by means of afixed guide element 4, such as a ceramic thread guide with a lowcoefficient of friction.

Disposed downstream of the first interlacing jet 2 is a stretching area13, in which a stretching unit or feed unit is provided, formed by asecond pair of rollers 15,17, the first of which is driven and thesecond is idle, forming a nip through which the yarns are fed. Theperipheral speed of the rollers 15 and 17 and the peripheral speed ofthe pair of rollers 7A, 7B are coordinated with each other to applystretch or to relax the elastic and covering yarns.

Disposed downstream of the stretching unit 15, 17, is a secondinterlacing jet, indicated as a whole with 19, which may be of a typeknown per se, and which—in this embodiment—is the process jet, that is,the one that coats the elastic yarn by means of the covering yarn.

A first elastic yarn F1, unwound from a first spool R1 of elastic yarnis fed through the nip defined by the stretching rollers 15, 17 formingthe stretching unit 13. The spool R1 is unwound by a driven unwindingroller 35 with which it is in contact. The speeds of the unwindingroller 35 and of the rollers 15, 17 are adjustable to apply the requireddegree of stretch to the yarn F1. Moreover, the speed of the rollers 15,17 can be adjusted with respect to the speed of the pair of rollers 7A,7B to apply a degree of stretch to the yarn FT which is either equal toor different than the stretch applied to the yarn F1, or also to slackenthe yarn FT. The yarn F1 fed from the spool R1 passes through the firstinterlacing jet 2 adjacent to the textured covering yarn FT. As the jet2 is inoperative during normal feed of the two yarns FT and F1, it hasno action on these yarns.

The spool R1 is supported by an arm 37A oscillating about an axis 39orthogonal to the plane of the figure. In addition to the oscillatingmovement, controlled by a piston-cylinder actuator 41, the arm 37A isprovided with a translating movement in a direction parallel to thelongitudinal extension of the arm, controlled by a furtherpiston-cylinder actuator 43. A further arm 37B, essentially the same asthe arm 37A, is hinged on the same axis 39, and its oscillating movementabout the axis 39 is controlled by a further piston-cylinder actuator,not visible and hidden from view in FIG. 2 by the actuator 41. The arm37B is also provided with a translating movement parallel to thelongitudinal extension thereof, controlled by an actuator similar to theactuator 43 and not visible in the figure.

The oscillating arm 37B supports a second spool R2 on which a secondelastic yarn F2 is wound. The spool R2 is (in the arrangement in FIG. 2)in a standby position to replace the spool R1 when the latter isfinished. The position of the two arms 37A, 37B can be exchanged thanksto the oscillating and extending/retracting movements of the armsobtained with the actuators 41, 43.

The yarn F2 is prepared along a standby path which extends downwardsfrom the spool R2 through the first interlacing jet 2 to a retainingmember 20, which has a suction mouth, inside which the head or free endof the second elastic yarn F2 is inserted. A mechanical retaining systemcan be associated with the mouth of the retaining member 20, so thatduring standby before replacing the yarn F1 with the yarn F2, suctionthrough the mouth can be deactivated and the free end of the yarn F2 iswithheld only mechanically. During exchange of the two spools R1 and R2the yarns F2 will, instead, be sucked by the mouth for reasons whichshall later become apparent.

The retaining member 20 is adjacent to the pair of rollers 15, 17 andpositioned rearwards with respect to the roller 17, that is, on theopposite side—with respect to the spool R2—of a vertical planecontaining the axis of the roller 17.

Along its path from the spool R2 to the retaining member 20 the secondelastic yarn F2 rests on a deflecting element 6 provided with a movementorthogonal to the plane in FIG. 2. The deflecting element can consist ofa cylinder made of ceramic or another material with low coefficient offriction, connected to the rod of a piston-cylinder actuator. Retractionof the rod of the piston-cylinder actuator releases the second elasticyarn F2 from the deflecting element 6 when the finished spool R1 must bereplaced with the spool R2, or when the yarn F1 breaks and must bereplaced with the yarn F2.

The deflecting element 6 withholds the second elastic yarn F2 standingby out of the range of action of a sensor 59, disposed along the path ofthe elastic yarn F1, between the spool R1 and the first interlacing jet2. The sensor 59, for example an optical sensor, detects passage of theelastic yarn F1 and provides a signal to start the cycle to replace thespool R1 with the spool R2, when delivery of the yarn F1 from the spoolR1 is interrupted. By keeping the yarn F1 out of the range of detectionof the sensor 59, this prevents operation of said sensor from beingdisturbed.

Downstream of the stretching unit 15, 17 the two yarns F1 and FT followa common path to the second interlacing jet 19, inside which, in a wayknown per se, the elastic yarn F1 is covered with the yarn FT to form acomposite or interlaced yarn FC.

Downstream of the interlacing jet 19 this composite yarn FC reaches thenip of a feed unit 53 formed by a third pair of rollers, consisting of adriven roller 54 and an idle roller 56. The peripheral speed of therollers 54, 56 is connected to the speed of the rollers 15, 17 of theunit 13, so that the yarns F1 and FT and the yarn FC which are betweenthese two pairs of rollers are subjected to the desired degree ofrelaxing and/or stretching.

Downstream of the feed unit 53 the yarn FC is deflected and guided by afork 52 and reaches a winding area, indicated as a whole with 55, whereit is wound on a winding tube T to form a cop BC of composite yarn.Positioned in the winding area 55 are mechanisms, known per se and notdescribed herein, which automatically unload the cops BC as they arecompleted and replace each completed cop BC with a new winding tube T.The number 57 generically indicates a device which: interrupts thecomposite yarn FC at the end of winding a cop BC; withholds, with asuction mouth, the yarn which continues to be delivered during the phaseto replace the cop BC with a new winding tube T and to replace the spoolof elastic yarn R1 with the spool R2; and resumes winding of the yarn FCon the new winding tube f. The device 57 is shown in greater detail inthe views in FIGS. 3, 4 and 5, which represent it in three differentoperating positions, according to III-III in FIG. 1.

In FIG. 3 the device 57 is shown in standby position before starting towind a new cop BC of interlaced yarn FC. The reference T indicates thetube which is used for winding and 60 indicates a ring, known per se,coaxial to the tube T and used to start winding the yarn on the tube.The tube T and the cop BC being formed thereon are made to rotate by adriven roller 54 positioned underneath (see FIG. 1), to ensure aconstant peripheral speed as the diameter of the cop being formedvaries. The number 56 indicates a thread guide or “traverse device”which with an alternating oscillating or translating movement accordingto the double arrow f56 distributes the turns of yarn on the tube T andon the cop BC being formed thereon.

The device 57 includes an arm 62 hinged about an axis 64 approximatelyorthogonal to the plane in FIGS. 3, 4, 5 and which carries a frontallyopen suction conduit, indicated with 66, a fork 68, with a translatingmovement according to f68 along the arm and parallel to the suctionconduit 66, and a guiding member 70 integral with the conduit 66, todraw the yarn towards the mouth of the suction conduit 66.

In the arrangement shown in FIG. 3, the yarn FC is sucked into theconduit 66. In this phase, the yarn may actually be composed only of thecovering yarn FT and not of the interlaced yarn FC, as the elastic yarnF1 or F2 previously delivered from the corresponding spool R1 or R2finishes in this phase, while the yarn FT is continuously fed even ifthe elastic yarn F1 or F2 is missing. However, as mentioned above, ifthe cop BC is replaced with a new winding tube T before the spool R1 orR2 of elastic yarn finishes (as the spool has enough yarn to produce,for example, two cops of composite yarn FC), in the phase to replace thecop BC with the tube T the device will suck composite yarn inside theconduit 66 until the new winding operation starts up.

After the yarn F1 (finished or broken) has been replaced with the yarnF2 (in the manner described in greater detail below) and the interlacingjet has started to produce composite yarn FC with the yarn F2 covered bythe yarn FT, the interlaced or composite yarn FC can start to be woundon the new tube T, which for this purpose is rotated about its axis.

By means of the fork 68, the yarn FC is drawn adjacent to the ring 60,which rotates integrally with the tube and grips the yarn to wind itaround said tube. The phase to draw the yarn FC adjacent to the ring 60is shown in FIG. 4. While the yarn forms the first winding turn on thetube T, a blade (not shown) cuts the yarn to separate it from theportion thereof which is inside the suction conduit 66. This produces afree end of yarn which remains anchored to the tube through the effectof winding. By continuing to wind the yarn FC delivered to the tube Tthereon, the path of the yarn FC between the guiding fork 52 and thetube T is intercepted by the thread guide 56 which engages the yarn andconsequently starts to distribute it along the entire axial extension ofthe tube with an alternating movement according to the double arrow f56.

After winding a cop BC on the tube T, the arm 62 is brought to theposition shown in FIG. 5 with the guiding member 70 disposed tointercept the path of the yarn FC drawn by the thread guide 56 in thealternating movement thereof. The guiding member 70 has a slantedsurface 70A which, when intercepted by the yarn FC, makes the latterrise to the mouth of the suction conduit 66. Simultaneously, the yarn FCis cut by a blade (not shown and carried by the thread guide 56) in anintermediate position between the finished cop and the guiding member70. The free end downstream of the cut is wound on the cop BC which isthen removed, while the free end upstream of the cut is inserted intothe suction conduit 66, which (as described above) starts to suck theyarn; the yarn continues to be delivered while the spool of elastic yarnis changed and the completed cop BC is replaced with a new tube. Fromthis position, the arm 62 returns to the position in FIG. 3 standing byfor a new winding process to start up as soon as the interlacing jet 19starts to deliver the completed yarn FC again, that is, after feeding ofthe new elastic yarn F2 starts.

Overall operation of the device described above is illustrated below. Inthe configuration shown in FIG. 2, the covering yarn FT, texturedupstream of the pair of rollers 7A, 7B, is fed to the stretching unit15, 17 and from here to the interlacing jet 19. Parallel thereto, theelastic yarn F1, delivered from the spool R1 which is turned by theunwinding roller 35, is also fed to the stretching unit 15, 17 and thento the interlacing jet 19. The composite yarn FC is wound on the cop BCbeing formed on the winding tube T supported by arms 56 in the windingarea 55. The second elastic yarn F2 is in standby position with theinitial free end engaged by the retaining member 20 and deflected by thedeflecting element 6 so as not to interfere with the sensor 59. Theyarns F1 and FT travel through the first interlacing jet 2, which istemporarily inoperative.

The phase to exchange the spool R1 with the spool R2 and to replace thecop BC with a new tube T is started when the sensor 59 detects that thefirst elastic yarn F1 delivered from the spool R1 has been finished orinterrupted. During this phase, the textured covering yarn FT continuesto be delivered without interruption, preferably at an essentiallyconstant speed. The sensor 59 can be replaced by another type of sensor,for example, which detects the diameter of the spool R1 about to finishor the amount of yarn F1 delivered. A sensor which detects the amount ofyarn wound on the cop BC, measured according to weight and/or length,may be combined with the sensor 59 or other equivalent device. Thisadditional sensor may be used to trigger the replacement process evenwhen the yarn F1 is not finished but the cop BC has been completed.

The following operations are carried out during the exchange phase. Thecomposite yarn FC is cut between the completed cop BC and the device 57,forming an head or tail end which is completely wound on the cop. Theother free end formed by the cut is withheld by the device 57 and suckedby the suction mouth 66 as described above with reference to FIGS. 3-5,and prepared to start the new winding cycle. In this way, the end partof the elastic yarn F1 and the covering yarn FT, which is still fedcontinuously, are sucked by the suction mouth and the yarn FT is keptadequately tensioned along the entire path thereof.

The arms 37A and 37B, and consequently the finished spool R1 and thestanding-by spool R2 of elastic yarn, are exchanged so that the arm 37Awith the finished spool R1 is positioned at a distance from theunwinding or delivery roller 35, and the arm 37B carries the spool R2into contact with the unwinding roller 35.

When the arm 37A has reached the final position with the finished spoolR1 in the appropriate position, the operator can replace the finishedspool R1, at any moment during the entire unwinding cycle of the spoolR2, with a new spool of elastic yarn which will subsequently be replacedin the same manner as the spool R2 when it in turn finishes or when theyarn F2 is interrupted, for example due to accidental breakage.

Before the spool R2 starts to deliver yarn by means of the unwinding ordelivery roller 35, suction is activated through the suction mouth ofthe retaining member 20, so that when spool R2 unwinding is activatedthrough rotation of the delivery or unwinding roller 35, the yarn F2starts to accumulate in or be drawn into this mouth. This phase lastsfor the minimum time required for the speed of the yarn F2 to reachapproximately the same value as the speed of the textured covering yarnFT, therefore for a relatively short time.

Once the two yarns F2 and FT, which are already inserted into the firstinterlacing jet 2, are moving at approximately the same speed, the firstinterlacing jet 2 is activated for a short period. The short jet ofpressurized air hits the two yarns FT and F2 in the channel of the jet2, causing them to join and the yarns therefore start to move forwardtogether towards the second interlacing jet 19. The air jet in theinterlacing jet 2 can be interrupted when the yarn F2 has been joined tothe yarn FT and is drawn by the latter towards the jet 19. As soon asthe yarn F2 reaches the second interlacing jet 19 production of thecomposite yarn FC, by the elastic yarn covered with the covering yarnFT, resumes. The second interlacing jet 19 can be temporarilydeactivated before this happens, to prevent it from acting on the yarnFT passing therethrough.

The deflecting element can be retracted after the replacement cycle hasstarted, that is, after the sensor 59 has detected interruption in thefeed of elastic yarn F1. In this way the sensor starts to detect passageof the yarn F2. When the composite yarn FC reaches the device 57, thisstarts winding the yarn FC on a new winding tube T, and the yarn is cut,thereby interrupting suction thereof through the mouth of the suctionconduit 66, as already described in greater detail with reference toFIGS. 3-5.

As is evident from the description above, the device is particularlyreliable, thanks to the fact that insertion of the second elastic yarnF2 into the process takes place in a very simple way with a minimumnumber of moving parts. In actual fact, the only movement is thedeflecting device 6, which is a very simple member with a reducedvolume. Moreover, movement thereof does not require to be perfectlysynchronized with exchange of the spools R1, R2, as its sole purpose iskeeping the yarn F2 out of the range of the sensor 59, while the yarn F2is joined to the yarn FT and inserted into the process jet 18 withoutthe movement of members and in particular without movement of theinterlacing jets 2 and 19. These jets can also be produced in aconfiguration that does not have controllable opening and closingsystems for yarn insertion.

In the exemplary embodiment described above, reference was made to amachine or device provided with three pairs of feed rollers 7A, 7B; 13,15 and 54, 56. Nonetheless, according to a different embodiment of thedevice, the pair of rollers 54, 56 can be eliminated, as can one of thetwo interlacing jets. A solution of this type is illustrated in FIG. 6,where the central part of the device, is shown, similarly to FIG. 2,while the remaining parts remain essentially unchanged with respect towhat is described with reference to FIGS. 1 to 5.

In FIG. 6, the same numbers indicate parts the same as or equivalent tothose in the previous figures. The interlacing jet 19 has beeneliminated and only the first interlacing jet, indicated with 2X,remains along the path of the yarns, which here performs the dualoperation of joining the yarns F2 and FT and covering the elastic yarnF1 or F2 with the yarn FT.

To prevent the second elastic yarn F2, standing by to replace the firstelastic yarn F1 being processed, from interfering with operation of thejet 2X and with operation of the sensor 59, in this case the initialportion of the yarn F2 is withheld by a double deflecting element 6, 8.This element can consist of a pair of piston-cylinder actuators, withtwo deflecting members coated in a material with low coefficient offriction (typically a ceramic material) associated with the rods of thepiston. The arrangement of the two deflecting members is such that byengaging the free end of the yarn F2 with the retaining member 20 andpositioning the deflecting members in their active position, the initialportion of the yarn F2 is in front and out of the interlacing jet 2X. Itwould also be possible to use a single deflecting element 8, suitablypositioned to hold the yarn F1 standing by out of the detection range ofthe sensor 59, and out of the inner channel of the interlacing jet 2X.

When the sensor 59 detects interruption of the first elastic yarn F1, itenables starting of the replacement cycle. As in the previous case, thecovering yarn FT continues to be fed, essentially at the same speed,through the interlacing jet 2X, which may be deactivated for a part ofor for the entire cycle to replace or exchange the yarns F1 and F2. Thecop BC of composite yarn FC is replaced with a new tube T, while thecovering yarn FT is accumulated by the suction mouth associated with thewinding system of the cops BC. The position of the arms 37A, 37B isexchanged, or more precisely the arm 37B is carried with the spool R2 incontact with the unwinding or delivery roller 35, while the arm 37A isplaced in a position in which the operator can easily replace thefinished spool R1 with a new spool.

Once the new tube T is in position and is turning (or even slightlybefore this moment) start-up of feed of the yarn F2 is enabled. Themouth of the retaining member 20 sucks the yarn F2, while with acoordinated movement the deflecting element 6, 8 is taken to theretracted position, so that the yarn F2 enters the detection range ofthe sensor 59 and the interlacing jet 2X and the latter is activated.Synchronization of the various operations is such that the new elasticyarn F2 is engaged with the covering yarn FT and, through the jet 2X,combined feed of the yarns F2 and FT and, consequently, production ofthe composite yarn FC, starts.

In this second solution, the device is further simplified throughelimination of the third feed unit 53, with its rollers 54 and 56. Theeffect of stretching and/or relaxing on the yarns being processed isobtained by coordinating the feed speeds of the feed unit 7A, 7B, of thefeed unit 13 formed of the rollers 15, 17 and of the unwinding ordelivery roller 35. More specifically, the elastic yarn F1 or F2 isstretched between the delivery or unwinding roller 35 and the unit 13,setting the peripheral speed of the rollers 15, 17 to a value higherthan the peripheral speed of the roller 35, while the covering yarn FTcan be stretched or relaxed by acting on the peripheral speed ratio ofthe rollers 15, 17 on the one hand and the rollers 7A, 7B on the other.

FIGS. 7A, 7B schematically show the interlacing jet 2X and thedeflecting member 8. The jet 2X has a channel 71 produced in a block 72.A pressurized air nozzle fed by a compressed air line 73 is disposedtransversely to the channel 72. In FIG. 7A the covering yarns FT and thefirst elastic yarn F1 are fed through the channel 72. The second elasticyarn F2 is in the standby position, with the initial free end engaged inthe mouth of the retaining member 20. A mechanical retaining device (notshown) can be associated with the suction mouth to allow suction toremain inactive, until the phase to exchange the spools R1, R2 starts.

In this standby position the yarn F2 rests on a ceramic coated rod 8A ofa piston-cylinder actuator 8B. The similar piston-cylinder actuator,forming the member 6 is not shown in FIG. 7 and is positioned above thesensor 59. In this way the yarn F2 is withheld standing by in an inletarea of the jet 2X, defined by an asymmetrical V-shaped profile, formedby sides 74, 75. In the example illustrated, through the effect of theoffset position of the retaining member 20, the yarn F2 rests on theside 75. A slit which leads into the channel 71 extends from the vertexof the V-shaped profile.

When the yarn F2 is to be brought into the process, it is released fromthe members 6, 8 (or by the member 8 when the member 6 is not provided)and, through the effect of the tension applied by suction of the mouthassociated with the retaining member 20, it is positioned at the vertexof the V-shaped profile 74, 75, passes through the slit therein and fromthere enters the process channel 71 of the jet 2X, to take the conditionin FIG. 7B, in which the yarns FT and F2 are fed through the jet.

The same type of jet can be used as jet 2 in the configuration in FIG.2. In this case, the yarns FT and F2, on which the jet performs noaction, pass through the conduit 71, while the yarn F2 is standing byinside said conduit until the yarn F1 finishes.

It will be understood that in the configuration in FIG. 2 the secondelastic yarn F2 could also be withheld standing by in front of thechannel of the jet 2, with a double deflecting mechanism as in theexample in FIG. 6.

A further embodiment of the invention is shown in FIGS. 8, 9 and 10.With particular reference to said figures, number 101 indicates as awhole the device for automatic threading of the elastomer yarn in amachine for the production of interlaced composite yarns 102, startingfrom a covering yarn 120 and from an elastomer yarn 121.

The covering yarn 120 is unwound continuously along a path defined by aseries of rollers made to rotate independently by relative spindles,comprising at least a drawing spindle 103 and a stretching spindle 104,and is fed to an air jet interlacing jet 105.

The interlacing jet 105 is simultaneously fed continuously with a firstelastomer yarn 121, to obtain interlacing of the covering yarn 120 withthe elastomer yarn 121, thus covering the elastomeric yarn 121 with thecovering yarn. The first elastomer yarn 121 is unwound from a firstspool 123 prearranged in a working position on the machine.

A second spool 124 of elastomer yarn 122 is prearranged in a stand-byposition and is suitable to be transferred to the aforesaid workingposition upon interruption of feed of the first elastomer yarn 121, byany suitable means, such as the ones described in more detail withrespect to the previous figures.

According to the present invention, the free end of the second elastomeryarn 122 is withheld, in a retaining area upstream of the interlacingdevice 105, by a tubular retention member 106 suitable to be connectedto appropriate suction means.

It must be observed that the second elastomer yarn 122 is unwoundlinearly from the second spool 124 to the inlet of the suction member106, disposed in said retaining area, in which the free end of the yarn122 is withheld.

Arranged in proximity to the retaining area of the free end of thesecond elastomer yarn 122, in practice immediately above the suctionmember 106, is a coupling member 110 through which the covering yarn 120and the first elastomer yarn 121 are conveyed continuously, to be fedtogether to the air jet interlacing device 105.

Substantially, said coupling member 110 is an interlacing jet composedin substance by an operating head 111 bearing a fork 112 which defines athrough channel 113, with a vertical axis, for the yarns 120 and 121;the channel 113 of the interlacing jet 110 is open at the front forinsertion of said yarns 120, 121. The fork 112 is preferably made of aceramic material.

In particular, the fork 112 shapes a flared inlet 114, prearranged atthe level of which is the portion of the second elastomer yarn 122 whichis unwound linearly from the second spool 124 to the suction member 106which retains its free end.

Associated with the operating head 111 is a conduit 115 to deliver apressurized air jet, suitable to be connected to conventional means forcompressed air feed. The conduit 115 leads transversely into the channel113, by an appropriate hole produced transversely to the fork 112.

The operating head 111 is suitable to be made to move in a horizontaldirection by an alternate actuator member 116, for example a pneumaticcylinder, connected to a support 117 fixed to the frame of the machine.This support 117 also has a deflecting roller 118, freely rotating,suitable to prearrange the covering yarn 120 according to a verticaldirection essentially aligned with the axis of the channel 113 of thefork 112.

Moreover, a sensor member 107 is positioned above the interlacing jet110. The sensor member 107 is suitable to detect interruption of feed ofthe first elastomer yarn 121, to control transfer of the second spool124 of elastomer yarn to the working position and corresponding transferof the first spool 123 of elastomer yarn to the stand-by position.

The method for automatic change of the elastomer yarn is easilyunderstandable from the description above.

During normal operating conditions of the machine, the covering yarn 20and the first elastomer yarn 121, being unwound from the relative spool123 disposed in the working position, are conveyed parallel through theinterlacing jet 110, 111 and then fed together to the second interlacingjet 105. The second elastomer yarn 122, the first portion of which hasbeen unwound from the relative spool 124 is disposed in the stand-byposition, and its free end is retained by the suction member 106,positioned slightly below the interlacing jet 110, 111.

It must be noted that, in this condition, the portion of the secondelastomer yarn 122 which extends from the second spool 124 to thesuction member 106 is disposed at the level of the flared inlet 114 ofthe fork 112 of the interlacing jet 110, 111.

When the sensor member 107 detects interruption in the feed of the firstelastomer yarn 121, due to the spool 123 finishing or the yarn breaking,it controls, in appropriate time relationship, transfer of the secondspool 124 of elastomer yarn to the working position and correspondingtransfer of the first spool 123 of elastomer yarn to the stand-byposition. It should be understood, however, that both in this embodimentas well as in the previous ones, that the stand-by and working positionsof the two elastic yarn spools might be fixed, i.e. the position mightnot change when the yarn is put into the process.

Simultaneously, by means of the alternate actuator member 116, movementof the interlacing jet 110, 111 is performed in the direction transverseto the direction of feed of the yarns, so as to come into contact withthe second elastomer yarn 122.

In practice, the head 111 moves linearly between a withdrawn position,occupied in normal operating conditions to feed the yarns to theinterlacing jet 105, and a forward position, indicated with the dashedline 111 a, in which the second yarn 122 is inserted in the channel 113of the fork 112 of the head 111. In this forward position, by means ofthe conduit 115, a pressurized air jet is delivered to the interlacingjet 110, 111 to join the second elastomer yarn 122 with the coveringyarn 120. Simultaneously, the free end of the second elastomer yarn 122is released by the suction member 106.

The interlacing jet 110, 111 is then moved again to the withdrawnposition of normal operation, to resume feed of the yarns 120, 122 tothe interlacing jet 105.

The method and device described thus attain the object of performing, ina safe and efficient way, automatic threading of the elastomer yarn inmachines for the production of interlaced yarns, in particular avoidingpossible breakages of the elastomer yarn.

In fact, the elastomer yarn disposed in the stand-by position is unwoundlinearly for a short portion from the relative spool to the suctionmember which withholds the free end, in an area relatively far from theinterlacing device 105. At the moment of automatic change of the spool,this elastomer yarn is therefore not subject to handling, rubbing orother steps which could cause breakage thereof.

This arrangement also considerably facilitates periodic arrangement ofthe spool of elastomer yarn in the stand-by position, it beingsufficient for the free end of this yarn to be taken to the level of theinlet of the suction member using conventional instruments.

A peculiarity of the method and of the device according to the presentinvention is constituted by the fact that when the spools are changedthe new elastomer yarn is joined locally with a pressurized air jet tothe covering yarn, which advances continuously, so that parallel feed ofthe two yarns to the interlacing device resumes immediately.

Obviously, it is possible for insertion of the elastomer yarn to beperformed with the machine stopped, as well as with the machine running.

The means for replacing the cop of composite yarn are not shown in FIGS.8, 9 and 10: they can be designed as in the previous embodiments.

It is understood that the drawing only shows practical embodiments ofthe invention, which may vary in forms and arrangements, without howeverdeparting from the scope on which the invention is based.

1. A method for the production of a composite yarn and for automaticreplacement of spools of elastic yarn, the method comprising the stepsof: feeding covering yarn along a feed path such that said covering yarnpasses through at least a first interlacing jet; delivering a firstelastic yarn from a first spool such that said first elastic yarn passesthrough the first interlacing jet; coating the first elastic yarn withsaid covering yarn to form composite yarn and winding the composite yarnon a cop; arranging a second spool of a second elastic yarn in astand-by position; withholding an initial portion of said second elasticyarn in an area of said first interlacing jet; replacing the cop ofcomposite yarn with a new tube when delivery of said first elastic yarnis interrupted; releasing said initial portion of the second elasticyarn after delivery of said first elastic yarn is interrupted;automatically replacing said first spool of elastic yarn with saidsecond spool of elastic yarn when delivery of said first elastic yarn isinterrupted joining said covering yarn and said second elastic yarn viathe first interlacing jet to resume forming said composite yarn; andwinding the composite yarn on said new tube after said second elasticyarn has been covered with said covering yarn.
 2. Method as claimed inclaim 1, wherein the initial portion of the second elastic yarn iswithheld by a retaining member.
 3. Method according to claim 2, wherein:said initial portion of the second elastic yarn is engaged by adeflecting element; and said deflecting element is controlled to releasesaid initial portion of the second elastic yarn.
 4. Method as claimed inclaim 3, wherein said deflecting element withholds said second elasticyarn such that said second elastic yarn does not enter the firstinterlacing jet, the second elastic yarn being disposed to be insertedautomatically into said first interlacing jet when said deflectingelement releases said second elastic yarn.
 5. Method as claimed in claim4, wherein said second elastic yarn is inserted into the firstinterlacing jet via tension exerted by the retaining member.
 6. Methodas claimed in claim 1, wherein the second elastic yarn is inserted intosaid first interlacing jet and withheld therein until said delivery ofsaid first elastic yarn is interrupted.
 7. Method as claimed in claim 1,wherein said retaining member withholds said initial free end at leastpartly by suction.
 8. Method as claimed in claim 1, wherein feed of thesecond elastic yarn starts before joining to said covering yarn. 9.Method as claimed in claim 7, wherein the second elastic yarn deliveredbefore joining to the covering yarn is sucked by said retaining member.10. Method as claimed in claim 1, wherein the covering yarn and theelastic yarn pass through a nip, defined by a pair of rollers downstreamof said first interlacing jet.
 11. Method as claimed in claim 1, whereinthe composite yarn passes through a nip defined by a pair of rollers.12. Method as claimed in claim 1, wherein said elastic yarn is coveredwith said covering yarn via said first interlacing jet.
 13. Method asclaimed in claim 12, wherein: when delivery of said first elastic yarnis interrupted, said first interlacing jet is temporarily made to stopoperating while the covering yarn continues to be fed therethrough;after the second elastic yarn from the second spool starts to bedelivered through the first interlacing jet, said first interlacing jetis re-activated to join the second elastic yarn to said covering yarnand resume production of said composite yarn.
 14. Method as claimed inclaim 13, wherein said second elastic yarn is already standing by insidethe first interlacing jet when feed of the first elastic yarn isinterrupted.
 15. Method as claimed in claim 1, wherein said elastic yarnis covered with said covering yarn by a second interlacing jet, disposeddownstream of the first interlacing jet along the path of the coveringyarn.
 16. Method as claimed in claim 15, wherein said first interlacingjet is temporarily activated to join the covering yarn and the secondelastic yarn and subsequently de-activated, while the second interlacingjet remains active at least to produce the composite yarn covering theelastic yarn with the covering yarn.
 17. Method as claimed in claim 16,wherein said second interlacing jet is temporarily deactivated betweeninterruption of feed of the first elastic yarn and start of feed of thesecond elastic yarn.
 18. Method as claimed in claim 15, wherein whendelivery of said first elastic yarn is interrupted, the covering yarn isfed through the first inoperative interlacing jet; after delivery of thesecond elastic yarn from the second spool starts, the first interlacingjet is temporarily activated to join the second elastic yarn to saidcovering yarn and subsequently deactivated.
 19. Method as claimed inclaim 12, wherein: said covering yarn is fed through a first nip betweena pair of rollers, at least one of which is driven, and through saidfirst interlacing jet; the composite yarn delivered from said firstinterlacing jet is fed to a second nip between a second pair of rollers;said second pair of rollers has a lower peripheral speed with respect tosaid first pair of rollers to relax the covering yarn between saidsecond nip and said first nip; and the elastic yarn is fed by a deliveryroller through said first interlacing jet, the delivery roller having alower delivery speed than the speed of said second pair of rollers, tosubject said elastic yarn to a stretching effect between said second nipand said delivery roller.
 20. Method as claimed in claim 1, wherein saidcovering yarn is a textured yarn, preferably a multiple filamenttextured yarn.
 21. Method as claimed in claim 20, wherein said coveringyarn is textured in line upstream of said first interlacing jet. 22.Method according to claim 1, further comprising the steps of:continuously feeding said covering yarn to a second interlacing jet;simultaneously feeding to said second interlacing jet said first elasticyarn, said first elastomer yarn being unwound from said first spool,disposed in a working position, such that said covering yarn isinterlaced with said first elastic elastomer yarn; withholding a freeend of said second elastic yarn, wound on said second spool, disposed ina stand-by position, in a retaining area; detecting interruption of feedof said first elastic yarn, to control, in appropriate timerelationship, transfer of said second spool of elastic yarn to saidworking position and transfer of said first spool of elastic yarn tosaid stand-by position; performing a relative movement of said coveringyarn with respect to said second elastic yarn, in proximity to saidretaining area of said free end of the second elastic yarn, such thatsaid covering yarn contacts said second elastic yarn; and associatingsaid second elastic yarn with said covering yarn using said firstinterlacing jet, simultaneously releasing said free end of the secondelastic yarn, to resume feed of said yarns to said second interlacingjet.
 23. Method as claimed in claim 22, wherein said second elastic yarnis unwound linearly from said second spool to said retaining area,positioned upstream of said second interlacing jet.
 24. Method asclaimed in claim 22, wherein said free end of the second elastic yarn iswithheld in the retaining area by suctions means.
 25. Method as claimedin claim 22, wherein said covering yarn and said first elastic yarn areconveyed continuously through said first interlacing jet such thatalternate motion is created via said first interlacing jet in adirection transverse to the direction of feed of said yarns, wherebysaid covering yarn contacts said second elastic yarn.
 26. A device forthe production of a composite yarn, the device comprising: a firstinterlacing jet; a covering yarn feed path extending toward said firstinterlacing jet; an elastic yarn feed path extending toward said firstinterlacing jet, said covering yarn and said elastic yarn formingcomposite yarn; supporting means for arranging at least a first spool ofelastic yarn and at least a second spool of elastic yarn; windingmembers winding the composite yarn on a cop being formed; aninterruption device, said interruption device interrupting feed of thecomposite yarn to said cop being formed, said interruption devicestarting winding the composite yarn on a new winding tube; a retainingmember associated with said first interlacing jet to withhold an initialfree end of the elastic yarn of said second spool; a sensor detectinginterruption of feed of said first elastic yarn to said firstinterlacing jet; a control element controlling release of said initialfree end of the elastic yarn of said second spool when said sensordetects an interruption in the feed of the first elastic yarn to saidfirst interlacing jet.
 27. Device as claimed in claim 26, wherein saidretaining member is a suction member.
 28. Device according to claim 26,further comprising a deflecting element arranged to withhold an initialportion of said second elastic yarn during delivery of the first elasticyarn to the first interlacing jet.
 29. Device as claimed in claim 28,wherein: said retaining member and said deflecting element are disposed,with respect to said first interlacing jet, such that said retainingmember and said deflecting element withhold the second elastic yarn in aposition outside of said interlacing jet; and the retaining membermaintains said second elastic yarn in tension such that said secondelastic yarn is inserted into said first interlacing jet when thedeflecting element releases said second elastic yarn.
 30. Device asclaimed in claim 26, wherein said first interlacing jet includes an airjet, said elastic yarn being covered with covering yarn via said airjet.
 31. Device as claimed in claim 30, further comprising: a first pairof drawing rollers defining a first nip along the feed path of thecovering yarn upstream of said first interlacing jet; and a second pairof drawing rollers defining a second nip, downstream of said firstinterlacing jet, and wherein said second pair of rollers are controlledsuch that said second pair of rollers rotate at a lower peripheral speedthan a peripheral speed of said first pair of rollers.
 32. Device asclaimed in claim 31, further comprising a delivery roller to deliver theelastic yarn, wherein a delivery speed of said delivery roller is lowerthan the peripheral speed of the rollers of said second pair.
 33. Deviceas claimed in claim 28, wherein said retaining member and saiddeflecting element are disposed, with respect to said first interlacingjet, such that the second elastic yarn is located inside said firstinterlacing jet.
 34. Device as claimed in claim 26, wherein a secondinterlacing jet is located downstream of said first interlacing jet,said elastic yarn and said covering yarn being delivered to said secondinterlacing jet, said second interlacing jet covering the elastic yarnwith the covering yarn.
 35. Device as claimed in claim 34, wherein saidfirst interlacing jet is controlled such that said first interlacing jetis activated only temporarily to join the second elastic yarn to thecovering yarn.
 36. Device as claimed in claim 34, wherein a third pairof drawing rollers are disposed downstream of said second interlacingjet, said third pair of drawing rollers defining a nip through which thecomposite yarn delivered from the second interlacing jet passes. 37.Device as claimed in claim 26, further comprising a texturing stationfor said covering yarn.
 38. Device as claimed in claim 26, wherein saidsupporting means maintains said first spool in a working position andsaid second spool in a standby position, said support meansautomatically removing the first spool from said working position andtransferring the second spool from the standby position to the workingposition when feed of said first elastic yarn is interrupted.
 39. Deviceas claimed in claim 26, wherein said supporting means of the first andof the second spool of elastic yarn are controlled such that areplacement cycle of the first spool of elastic yarn with the secondspool of elastic yarn is started following interruption of feed of thefirst elastic yarn.
 40. Device as claimed in claim 39, wherein saidsensor detects the end of the elastic yarn of said first spool. 41.Device as claimed in claim 26, wherein said first interlacing jet ismovable such that the second elastic yarn enters said first interlacingjet via movement of said first interlacing jet.
 42. Device as claimed inclaim 41, wherein said first interlacing jet is movable from a withdrawnposition to a forward position in a direction transverse to a directionof feed of said yarns, wherein said first interlacing jet is activatedto join said second elastic yarn to said covering yarn.
 43. Device asclaimed in claim 26, further comprising a collecting member, saidcollecting member collecting the covering yarn delivered betweeninterruption of the first elastic yarn and start of delivery of thecomposite yarn formed with the second elastic yarn.
 44. Device asclaimed in claim 43, wherein said collecting member comprises a suctionmember.
 45. Device as claimed in claim 26, wherein an oven is disposedalong the path of said covering yarn upstream of said first interlacingjet.
 46. A method for the production of a composite yarn and forautomatic replacement of spools of elastic yarn, the method comprisingthe steps of: feeding covering yarn along a feed path to a firstinterlacing jet; delivering a first elastic yarn from a first spool tothe first interlacing jet; coating the first elastic yarn with saidcovering yarn to form composite yarn; winding the composite yarn on acop; arranging a second spool of a second elastic yarn in a stand-byposition; holding an initial portion of said second elastic yarn in anarea of said first interlacing jet; replacing the cop of composite yarnwith a new tube after delivery of said first elastic yarn isinterrupted; releasing said initial portion of the second elastic yarnafter delivery of said first elastic yarn is interrupted, said firstspool of elastic yarn being automatically replaced with said secondspool of elastic yarn when delivery of said first elastic yarn isinterrupted, wherein the feed of covering yarn to said first interlacingjet decreases or stops when said first spool of elastic yarn isautomatically replaced with said second spool of elastic yarn; joiningsaid covering yarn and said second elastic yarn via the firstinterlacing jet to resume forming said composite yarn; and winding thecomposite yarn on said new tube after said second elastic yarn has beencovered with said covering yarn.